Birds' Mating Patterns Change with the Weather

March 02, 2012

Many different species of birds are monogamous — they may change partners over the course of their lives, but they're typically faithful. However, according to a new study by researchers from the National Evolutionary Synthesis Center and Columbia University, some birds are prone to infidelity and even "divorce." In fact, the scientist observed a connection between instances of birds being unfaithful to one another and severe weather fluctuations.

The researchers studied hundreds of bird species, focusing on those that require both parents to raise the chicks. They identified infidelity by finding birds that were raising the chicks born out of affairs, and found that there were higher instances of infidelity among birds that live in varying climates. Divorce tended to be more common in these regions as well. Birds will leave their mates to seek out new partners to increase the odds that their offspring will survive.

"Most apparently monogamous birds end up having multiple partners," said lead author Carlos Botero, now a postdoctoral fellow at the Initiative in Biocomplexity at North Carolina State University. "Mating with multiple partners improves the chances that at least one chick will have the genes to cope with the variable conditions to come. The quality of a potential mate depends on the context."

Botero goes on to offer the Galapagos finch as a prime example. Darwin noted that these birds developed specialized beaks to help them get food. Some of them have powerful beaks that help them crack open large, tough shells of seeds during the dry season, while others have smaller beaks that are better suited for finding food during the wet seasons, according to the news source.

A female finch may mate with males that have each kind of beak, but offspring from only one or the other might have a better chance of survival depending on the weather conditions when they are born. Of course, International Expeditions’ Galapagos island cruises[1] are the perfect opportunity for nature travel lovers to see the many different finches — both faithful and unfaithful — along with other creatures endemic to the South American archipelago.

These mating patterns and their relationship with the climate may indicate that birds have the ability to adapt to major changes in their environment. Whether man-made influences or natural shifts in the weather come along, this study could reveal that some birds will find ways to survive, even if it means divorcing their current mates.